1. Field
Example embodiments generally relate to sleeves usable in nuclear reactors for piping and component repair and replacement, such as to repair and replace piping in a Boiling Water Reactor (BWR) and jet pump sensing lines in BWRs.
2. Description of Related Art
Generally, BWRs include jet pumps as part of a recirculation system to effectively move coolant and moderator through a nuclear core. In order to evaluate operating conditions within the nuclear core, it may be desirable to monitor the flow rate through the core, including flow rate of coolant from the jet pumps. Typically, a jet pump sensing line is used to measure flow rate from the jet pumps by measuring a pressure differential between the inlet and nozzle of the jet pumps.
FIG. 1 is an illustration of related art BWR jet pump nozzles with jet pump sensing lines coupled to a diffuser at the base of the jet pump nozzles. The jet pump sensing lines 100 are shown attached on a lower diffuser 110 of each of a plurality of jet pumps 150. The sensing lines 100 connect to various points on the jet pump 150 in order to measure pressure differentials. The sensing lines 100 are typically welded or otherwise integrally coupled with the diffuser 110 and as such can be subject to flow-induced vibration in the jet pump 150.
The jet pumps 150 are typically installed within a BWR and only accessible during scheduled plant outages for refueling and repair. These outages typically occur at several month intervals, and thus components within the core, including the jet pumps and jet pump sensing lines, must operate for lengthy periods before being inspected and/or repaired.
Further, BWR core operating conditions include high levels of radioactivity due to fission occurring in the fuel rods. Radioactivity, particularly the neutron flux generated in an operating nuclear reactor core, degrades the material strength and elasticity of core components over time. Components within the core, including jet pump sensing lines 100, are thus subject to premature brittling and cracking due to this radiation exposure. Accordingly, flow-induced vibration and lengthy operating cycles coupled with radiation can cause jet pump sensing lines to crack, rupture or otherwise fail, preventing an effective and/or accurate measurement of core flow rate within the core.
Related art jet pump sensing line repair mechanisms, for example, U.S. Pat. No. 5,752,807, involves replacing an entire failed jet pump sensing line, or using a slip-fit shrink memory alloy coupling, which must be specially fitted for the jet pump sensing line to be replaced.